This invention generally relates to plastic containers and covers therefore; and more particularly, to a container and cover having a plurality of tabs which make the container and cover both child resistant and tamper evident.
Containers have long been provided with childproof features that make it difficult, if not impossible, for a child to open a container. In one prior art construction, a screw top cover for a pail includes a tab having an integral projection forming part of the skirt of the cover. Four triangular shaped, raised projections are formed at equally spaced intervals around the rim of the pail. As the cover is screwed down onto the top of the pail, the tab is pressed inwardly for the projection formed by the tab to slide behind one of the four projections formed on the pail. The design of the cover is such that when completely screwed down, the projection formed by the tab on the cover stops slightly beyond one of the projections formed on the pail. The cover tab now springs back so it has a vertical edge abutting the edge of the adjacent projection formed on the top of the pail. This prevents the cover from now being unscrewed unless the tab on the cover is depressed inwardly as the cover is rotated off the top of the pail. Such an operation is readily easy for adults to understand and perform, but not children. The above described construction, however, has drawbacks. The clearance between the tab on the cover and projection on the pail, when the cover is screwed down, is important. If the tab extends too far past a projection, it means the threads on the cover and pail are not properly engaged and leakage may occur. If the tab does not extend far enough, the threads may be too tight. In this circumstance, the cover may not properly close allowing a child to open it. Since many plastic containers are filled with hazardous materials, the potential for danger is increased.
Besides child resistance, containers have also been provided with tamper evident features that make evident if the container has been previously opened. Tamper evident features can, for example, prevent the addition of foreign substances to the container's normal contents. It has been reported, for example, that someone will steal an expensive item such as a watch by placing it in a container holding a relatively cheap, bulk material such as pool chemicals. At the check out counter, the thief pays only for the cheap bulk material. More seriously, people have been known to add various types of contaminants to a container. The contaminant can then cause serious injury, or death, if unknowingly mixed with other chemicals, or if a person ingests, or is exposed to the contaminant.
There have been other approaches to providing tamper evident and child proof containers. U.S. Pat. No. 4,930,656, for example, teaches a removable tear strip for a plastic cover. The strip seals the cover to the top of a container prior to its sale. The customer then tears off the strip before opening the container. U.S. Pat. No. 5,310,074 teaches a screw top container having a hidden locking mechanism that prevents children from removing the top. However, there is no provision for indicating if there has been tampering with the container. U.S. Pat. No. 5,915,575 teaches a screw top container having a locking mechanism incorporated into a cover for the container. The mechanism includes a lever pivotable about a vertical axis. While the mechanism makes it difficult for children to open the container, there is nothing to indicate if tampering has occurred. Finally, U.S. Pat. No. 6,006,942 is for a container with a locking mechanism having a lever pivotable about a horizontal axis. While resistant, there is again no provision of something to indicate tampering.